Three British teenagers have been killed in a head-on car crash in South Africa while on a gap-year trip round the world.

Childhood friends Nick Thompson, 19, Oli Mobsby and Ed Lowton, both 18, were returning from a safari expedition when the crash took place 70 miles north of Cape Town. They had taken A-levels at the same school and were due to start studying at York University in September.

Police said the car in which they were travelling was overtaking when it collided with an on-coming vehicle. The three occupants of that car were in a serious condition.

In a joint statement, the families of the teenagers said the friends had been "having the time of their lives".

"From the phone calls home, text messages, photographs, postings on Facebook and words from friends they made there, it was clear [they] were having the time of their lives.

"The families are very grateful for all the support we have had from their friends and the tributes paid to them. This includes floral tributes left at North Dorset Rugby Club, the minute's silence before rugby and football games and the memorial drinks and parties to celebrate their lives," the statement said.

The friends set off for South Africa in January after completing their studies at Gillingham School in Dorset last year. They were also planning to visit Thailand, Australia, Fiji, New Zealand and America.

The crash happened on 9 March.

Mr Mobsby, from Bourton, Dorset, and Mr Thompson, from Stalbridge, Dorset, both played rugby for North Dorset Colts. Mr Lowton lived in Shaftesbury, Dorset.

Mr Mobsby's father, Stephen Mobsby, said: "South Africa was the first stage in a gap year round-the-world trip that the boys had been planning and working towards since before they finished in the sixth form at Gillingham School. It was to be their great adventure before taking up their places at university."

Friends, family and teachers yesterday paid tribute to the trio on their Facebook sites. One of Mr Lowton's former teachers at Gillingham School, Lizzy Boston, said: "Ed – you know how much I enjoyed teaching you. I can still picture you with Nick, George and Dave in the back row of my classroom, always so cheeky and mischievous and making me and your peers laugh.

"Your wit was so refreshing and intelligent that I could never get cross with you. What an achievement to have lived such a fruitful life at such a young age and to have had such a positive influence and impact on those people you came across." A friend of the trio, Abbi Horsman, said: "You were truly such fantastic guys. I'm really going to miss you. There was never a dull moment with you around. You will never be forgotten, words can't describe how much everyone is going to miss you."

Mr Mobsby's friend Colette Davidson wrote: "I just want to say thank you so much for always being there for me, giving me advice on everything and always making the time to talk to me. I've never met anyone quite like you and probably never will. I'll always regret the times in which we didn't speak for the rest of my life but I'll treasure the memories I have forever."

The three occupants of the other car, a 59-year-old South African man and his sons, aged 25 and 23, are still in hospital with critical injuries.

A memorial service for the teenagers was held in Cape Town on Saturday. Their funerals will be held later this month and in April.